Thickener containing a cationic polymer and softening composition containing said thickener, in particular for textiles

ABSTRACT

A method for softening laundry employs a softening composition, which includes at least one thickener containing a cationic polymer obtained by polymerization:
         of a cationic monomer;   of a monomer with a hydrophobic nature, of formula (I):       

                         
wherein
     R1=H or CH 3      R2=alkyl chain having at least 16 carbon atoms   X=O, m≧5, y=z=0, or   X=NH, m≧z≧5, y=0, or   X=NH, m≧y≧5, z=0,
       of a nonionic monomer.

This is a continuation of U.S. patent application Ser. No. 14/064,856filed Oct. 28, 2013, now U.S. Pat. No. 9,018,154, which is a divisionalof U.S. patent application Ser. No. 13,683,919, filed Nov. 21, 2012, nowabandoned, which is a continuation of PCT/FR2011/051208, filed May 27,2011.

FIELD OF THE INVENTION

The present invention relates to a thickener/stabilizer, in particularused in softening compositions for laundry. It is a cationic polymerobtained by polymerization of cationic monomers and of monomers with ahydrophobic nature.

BACKGROUND OF THE INVENTION

The use of such thickeners in softening compositions makes it possibleto improve their rheological profile and therefore to modify theproperties of the softening formulation. Moreover, the role of thesoftener is to provide a much more pleasant feel by lubrication of theanimal textile fibres (wool in particular) and plant textile fibres(cotton) and of the synthetic fibres after treatment. It also providesantistatic properties by reducing the friction between fibres, itprovides sensations of freshness by virtue of the fragrancesincorporated, and it makes it possible to bring out the colours and tofacilitate ironing.

In the remainder of the description and in the claims, the expression“thickener” is intended to mean, without implied distinction, thickenerand/or stabilizer

Document WO 90/12862 describes a softening composition comprising acationic polymer which acts as a thickener. This polymer is very lightlycrosslinked in the presence of from 5 to 45 ppm of a crosslinking agentcomprising polyethylenic functions.

Document U.S. Pat. No. 6,864,223 describes a softening compositioncontaining polymers of the same type, but which are crosslinked to agreater extent (70-300 ppm) and combined with a softener of quaternizedester type and with a fragrance.

The publication Research Disclosure No. 429116, from January 2000,relates to the preparation of cationic polymers in inverse emulsions andto their use as thickeners in various compositions, such as, forexample, for fabric softeners.

Document WO 2005/053748 by the Applicant describes heavily crosslinkedcationic polymers (>300 ppm), used as thickeners of aqueouscompositions.

Patent application PCT/EP2009/050077, still by the Applicant, describescationic polymers, in the form of an inverse emulsion, which are veryheavily crosslinked and have a maximum insoluble material content of15%. These polymers can be used in softening compositions.

Document WO 97/36981 describes softening compositions which are stableand viscous by combining an acrylic thickener, as described in documentWO 90/12862, and an associative polymer of ethoxy/propoxy (EO/PO)surfactant type.

Documents EP 0 172 723 and EP 0 172 724 describe polymer compositionsand an inverse emulsion polymerization process for preparing anionic orcationic, linear or crosslinked polymers containing hydrophobic groupshaving more than 8 carbon atoms.

Document US 2004/052746 describes in particular a softening compositioncomprising a polymer obtained by polymerization of the following fourmonomers:

-   -   a vinyl monomer having a cationic or neutral amine group;    -   a nonionic and hydrophobic vinyl monomer;    -   an associative vinyl monomer; and    -   a semihydrophobic vinyl surfactant monomer.

In addition, it is specified that the presence of the semihydrophobicvinyl surfactant monomer is essential for the stability of the emulsionscomprising this copolymer.

Document EP 1 099 749 describes a softening composition comprising aneutral copolymer obtained by polymerization of:

-   -   a monomer based on acrylic acid or methacrylic acid;    -   a vinyl monomer; and    -   an associative monomer.

Document WO 2005/087188 describes an anti-adhesive substance forcosmetic preparations comprising the neutral terpolymer obtained inparticular by polymerization of:

-   -   dimethylaminoethyl methacrylate;    -   ethyl acrylate; and    -   beheneth-25 methacrylate.

Document WO 97/22640 describes a foaming agent comprising a terpolymerobtained by polymerization of:

-   -   a cationic monomer (DADMAC);    -   a vinyl monomer comprising an amide group; and    -   a vinyl monomer having a hydrophobic group and also a        hydrophilic group.

Document U.S. Pat. No. 4,454,060 describes a liquid detergentcomposition comprising a copolymer that can be prepared from:

-   -   an acrylamide-based monomer;    -   a cationic monomer; and    -   a monomer comprising a hydrophobic group.

Document EP 1 449 862 describes the use of a cationic polymer as athickener in a cosmetic or pharmaceutical composition, as a thickenerfor printing pastes for the textile industry, as a thickener forindustrial or household detergents or else in the petroleum industry.Said polymer comprises a cationic monomer, a neutral monomer and anonionic surfactant monomer.

It should, however, be noted that documents WO 2005/087188, WO 97/22640,U.S. Pat. No. 4,454,060 and EP 1 449 862 do not therefore relate tosoftening compositions.

Although the thickeners used in the fabric softener compositionsdescribed in the prior art certainly make it possible to thicken thecompositions, there is, however, a need to control the rheologicalprofile of the formulation better and to obtain an increased stabilityof the composition.

Indeed, the viscosity of such a composition is influenced by a verylarge number of parameters:

-   -   variable concentrations of softener (diluted to concentrated        form);    -   complex processes for use (agitation, temperature, batch or        continuous, etc.);    -   numerous regional specificities (South America, Asia, Europe,        North America).

It is also necessary to improve the compatibility between the thickeningpolymers and the softeners and therefore the stability of thecomposition.

Document WO 2008/036587 describes an antiperspirant compositioncomprising a modified hydrophobic cationic polymer. This polymer can beobtained by polymerization of the following four monomers:

-   -   a vinyl monomer;    -   a hydrophobic nonionic vinyl monomer;    -   an associative vinyl monomer; and    -   a semihydrophobic surfactant vinyl monomer.

The present invention proposes to solve in particular the followingtechnical problems:

-   -   improvement of the stability of the softening compositions;    -   increase in the thickening capacity of the polymers in the        softening compositions, thus making it possible to significantly        reduce the amount of polymer;    -   improvement of the rheological profile, regardless of the        concentration of the softener.

SUMMARY OF THE INVENTION

According to the present invention, it has been discovered that,surprisingly, the selection of specific hydrophobic monomers forpreparing a cationic polymer makes it possible to improve therheological profile and the stability of softening compositions,compared with the polymers of the prior art.

In addition, these polymers are more compatible with the otheringredients contained in the softening compositions and in particularthe softeners of quaternized ester type.

Finally, the use of this type of polymer makes it possible tosignificantly reduce the amount of polymer in the softening composition.

Without putting forward any theory, the Applicant explains theseimprovements: a better affinity between the hydrophobic parts of thecationic polymers (polymer/substrate interactions) and those of thesofteners, and an interaction between the hydrophobic parts of thepolymers themselves (polymer/polymer interactions).

More specifically, the present invention relates to a thickenercontaining a cationic polymer obtained by polymerization:

-   -   of at least one cationic monomer;    -   of at least one monomer with a hydrophobic nature, of formula        (I):

wherein

-   -   R1=H or CH3    -   R2=alkyl chain having at least 16 carbon atoms    -   X=O, m≧5, y=z=0, or    -   X=NH, m≧z≧5, y=0, or    -   X=NH, m≧≧y 5, z=0;    -   optionally of at least one nonionic monomer and/or of at least        one anionic monomer.

An alkyl chain is a saturated linear or branched acyclichydrocarbon-based chain of general formula C_(n)H_(2n+1).

In one preferred embodiment, the thickener according to the presentinvention comprises a cationic polymer, and more specifically a cationicterpolymer, obtained by polymerization:

-   -   of a cationic monomer;    -   of a monomer with a hydrophobic nature of formula (I):

wherein

-   -   R1=H or CH3    -   R2=alkyl chain having at least 16 carbon atoms    -   X=O, m≧5, y=z=0, or    -   X=NH, m≧z≧5, y=0, or    -   X=NH, m≧y≧5, z=0;        -   of a nonionic monomer.

According to another advantageous embodiment, the thickener according tothe present invention consists of said cationic terpolymer.

According to the invention, the cationic polymer may be crosslinked ornon-crosslinked. When said polymer is crosslinked, the crosslinking iscarried out optionally in the presence of a transfer agent in order tocontrol the molecular weight.

The cationic monomers are advantageously chosen from the groupcomprising diallyldialkylammonium salts, such as diallyldimethylammoniumchloride (DADMAC); acidified or quaternized salts of dialkylaminoalkylacrylates and methacrylates, in particular of dialkylaminoethyl acrylate(ADAME) and of dialkylaminoethyl methacrylate (MADAME); acidified orquaternized salts of dialkyl-aminoalkylacrylamides or methacrylamides,such as, for example, methacrylamidopropyltrimethylammonium chloride(MAPTAC), acrylamidopropyltrimethylammonium chloride (APTAC) and theMannich products, such as quaternized dialkylaminomethylacrylamides.

The acidified salts are obtained by means known to those skilled in theart, and in particular by protonation. The quaternized salts are alsoobtained by means known to those skilled in the art, in particular, byreaction with benzyl chloride, methyl chloride (MeCl), aryl chlorides,alkyl chlorides or dimethyl sulphate.

Advantageously, the content of cationic monomer represents between 25%by weight and 99.9% by weight relative to the weight of the cationicpolymer, preferably between 50% by weight and 99.5% by weight.

The monomers with a hydrophobic nature, or hydrophobic monomers, are offormula (I). Mention will particularly be made of ethoxylated cetylmethacrylate (EO 25) and ethoxylated behenyl methacrylate (EO 25) andmixtures thereof.

More advantageously, the hydrophobic monomer is ethoxylated behenylmethacrylate (EO 25).

The term “EO 25” signifies that the monomer with a hydrophobic naturecontains 25 ethoxy CH₂—CH₂—O units. In other words, m=25 for thecompound according to the formula (I).

Preferably, the content of hydrophobic monomer represents between 0.1%by weight and 20% by weight relative to the weight of the cationicpolymer, preferably between 0.5% by weight and 5% by weight.

As already indicated, the cationic polymer contained in the thickeneraccording to the invention may be prepared by polymerization of at leastone cationic monomer, of at least one monomer with a hydrophobic nature,and optionally of at least one nonionic monomer and/or of at least oneanionic monomer.

The nonionic monomers are advantageously chosen from the groupcomprising acrylamide, methacrylamide, N-vinylmethylacetamide orN-vinylformamide, vinyl acetate, vinylpyrrolidone, methyl methacrylateor other acrylic esters, or other ethylenically unsaturated esters, orelse other water-insoluble vinyl monomers, such as styrene oracrylonitrile.

Advantageously, the content of nonionic monomer represents between 0 and74.9% by weight relative to the weight of the cationic polymer, moreadvantageously between 0 and 30% by weight.

The anionic monomers are advantageously chosen from the group comprisingthe salts of monomers having a carboxylic function in addition to acarbon-carbon double bond, such as, for example, acrylic acid salts,methacrylic acid salts, and the salts of monomers having a sulphonicacid function, such as, for example,2-acrylamido-2-methylpropanesulphonic acid (ATBS) salts.

Preferentially, the content of anionic monomer represents between 0 and50% by weight relative to the weight of the cationic polymer, preferablybetween 0 and 20% by weight.

In one particular embodiment, the cationic polymer contained in thethickener according to the invention may be obtained by polymerization:

-   -   of chloromethylated dimethylaminoethyl methacrylate;    -   of acrylamide; and    -   of ethoxylated behenyl methacrylate (EO 25).

In another particular embodiment, the cationic polymer contained in thethickener according to the invention may be obtained by polymerization:

-   -   of chloromethylated dimethylaminoethyl methacrylate;    -   of acrylamide; and    -   of ethoxylated cetyl methacrylate (EO 25).

As already stated, the cationic polymer according to the invention canbe crosslinked in the presence of a crosslinking agent and optionally inthe presence of a transfer agent.

The crosslinking agent is advantageously chosen from the groupcomprising: methylenebisacrylamide (MBA), ethylene glycol diacrylate,polyethylene glycol dimethacrylate, diacrylamide, cyanomethyl acrylate,vinyloxyethyl acrylate or methacrylate, triallylamine, formaldehyde,glyoxal, compounds of glycidyl ether type, such as ethylene glycoldiglycidyl ether, epoxies, or a mixture of these compounds.

Advantageously, the content of crosslinking agent represents between 0and 10% by weight relative to the weight of the cationic polymer,preferably between 0 and 5% by weight.

The transfer agent, when it is present, is chosen from the groupcomprising: isopropyl alcohol, sodium hypophosphite, mercaptoethanol ora mixture of these compounds.

Advantageously, the content of transfer agent represents between 0 and5% by weight relative to the weight of the cationic polymer, preferablybetween 0 and 2% by weight.

The constituent cationic polymer of the thickener according to thepresent invention can be in liquid or solid form. It can be prepared bydispersion polymerization, by inverse emulsion polymerization, bymicroemulsion polymerization, or by gel polymerization, it beingpossible for the polymer obtained to be subsequently dried and isolatedin order to have a powder.

In one particular embodiment, the cationic polymer is in the form of aninverse emulsion comprising an oily phase, an aqueous phase, at leastone water-in-oil (W/O) emulsifier, at least one oil-in-water (O/W)emulsifier. The inverse emulsion generally comprises from 20% to 60% byweight, and preferably from 40% to 55% by weight, of linear, branched orcrosslinked cationic polymer.

The term “water-in-oil emulsifier” is intended to mean emulsifiers whichhave an HLB value that is sufficiently low to provide water-in-oilemulsions, such as the surfactant polymers sold under the name Hypermer®or such as sorbitan extracts, for instance sorbitan monooleate orsorbitan isostearate.

The term “oil-in-water emulsifier” is intended to mean emulsifiers whichhave an HLB value that is sufficiently high to provide oil-in-wateremulsions, such as ethoxylated sorbitan esters, for instance ethoxylatedsorbitan oleate with 20 equivalents of ethylene oxide (EO 20).

In the particular embodiment constituted by the inverse emulsion, asdescribed previously, the copolymerization of the precursor monomers iscarried out at a pH greater than 4 and preferably between 4 and 6.

The inverse emulsion generally contains from 1% to 10% by weight, andpreferably from 2.5% to 9% by weight, of water-in-oil (W/O) emulsifiersand from 2% to 10% by weight, and preferably from 2.5% to 6% by weight,of oil-in-water (O/W) emulsifiers.

The inverse emulsion contains an oily phase representing from 15% to40%, preferably from 20% to 25% of its total weight.

This oily phase can be either a commercial mineral oil containingsaturated hydrocarbons of paraffinic, isoparaffinic or cycloparaffinictype, having at ambient temperature a density of between 0.7 and 0.9, ora vegetable oil, or a synthetic oil, or a mixture of several of theseoils.

The inverse emulsion contains between 2% and 40% of water. It can alsocontain various additives, such as complexing agents, transfer agents orchain-limiting agents.

The process for preparing the inverse emulsion as previously defined iscarried out according to the following steps:

-   -   a) an aqueous solution containing the monomers and the optional        additives is emulsified in an oily phase in the presence of one        or more water-in-oil emulsifiers,    -   b) the polymerization reaction is initiated by introducing, into        the emulsion formed in a), a free radical initiator system and        then the reaction is allowed to take place,    -   c) when the polymerization reaction is finished, one or more        oil-in-water emulsifiers are introduced at a temperature below        50° C.

According to one variant of this process, the reaction medium resultingfrom step b) is concentrated by distillation, before step c) is carriedout.

According to another variant of this process, the reaction mediumresulting from step b) is completely dried. In this case, step c) is notcarried out.

According to another preferred implementation of the process, the pH ofthe starting aqueous solution is adjusted to a pH greater than or equalto 4 before step c) is carried out.

As already stated, it is also possible to concentrate or isolate thecationic polymer contained in the thickener according to the inventionby any of the techniques known to those skilled in the art. There are inparticular, numerous processes for obtaining a powder from inverseemulsions of polymers, which consist in isolating the active materialfrom the other constituents of the emulsion, such as, for example:

-   -   precipitation from a nonsolvent medium, such as acetone,        methanol or any other polar solvent in which the cationic        polymer is not soluble. Simple filtration then makes it possible        to isolate the polymer particle;    -   azeotropic distillation in the presence of an agglomerating        agent and of stabilizing polymer makes it possible to produce        agglomerates that are easily isolated by filtration before        drying the particle;    -   “spray-drying” consists in creating a cloud of fine emulsion        droplets in a stream of hot air for a controlled period of time.

The polymers of the invention, obtained in the form of a powder by anyone of the techniques described above, have the main advantage of beingproposed without solvent. They will therefore be quite particularlysuitable for compositions which are highly sensitive to residual odour,regulatory and/or toxicological profile problems.

The Applicant has discovered, surprisingly, that the use of thesespecific polymers makes it possible to significantly improve thecompatibility with softeners comprising a hydrophobic sequence. It alsomakes it possible more successfully to stabilize these softeningcompositions, in particular at acidic pH and in dispersed systems, andto develop viscosity profiles thus far difficult to envisage.

The selection of certain hydrophobic monomers according to the formula(I) and the polymerization thereof with the cationic monomers isresponsible for these unexpected properties.

Another subject of the present invention is therefore a softeningcomposition comprising at least one thickener as previously describedand also at least one softener.

DETAILED DESCRIPTION OF AN EMBODIMENT OF THE INVENTION

According to one preferred embodiment, the present invention relates toa softening composition comprising at least one thickener containing acationic polymer, and more specifically a cationic terpolymer, obtainedby polymerization:

-   -   of a cationic monomer;    -   of a monomer with a hydrophobic nature, of formula (I):

wherein

-   -   R1=H or CH₃    -   R2=alkyl chain having at least 16 carbon atoms    -   X=O, m≧5, y=z=0, or    -   X=NH, m≧z≧5, y=0, or    -   X=NH, m≧y≧5, z=0;        -   of a nonionic monomer.

According to another preferred embodiment, the present invention relatesto a softening composition comprising at least one thickener consistingof a cationic terpolymer obtained by polymerization:

of a cationic monomer;

of a monomer with a hydrophobic nature, of formula (I):

wherein

-   -   R1=H or CH₃    -   R2=alkyl chain having at least 16 carbon atoms    -   X=O, m≧5, y=z=0, or    -   X=NH, m≧z≧5, y=0, or    -   X=NH, m≧y≧5, z=0;        -   of a nonionic monomer.

The softening compositions, into which the polymers of the invention areintroduced, are used during or after the washing of textile materials.They are applied during washing, generally at the stage of the rinsecycle, where they are added to the rinsing water, or during the dryingcycle, where they are used dry, for example, as an impregnation agent ona woven or nonwoven fabric strip.

Advantageously, the content of thickener in the softening compositionrepresents 0.05% to 10% relative to the weight of the softeningcomposition or, preferably, 0.1 to 5%.

The textile material softening compositions are aqueous compositionscontaining softeners of quaternized ester type. These molecules are notsoluble in water. They have a cationic nature. They have a hydrophilicpart for affinity with the textile substrate, cellulose fibres, and ahydrophobic part (a long alkyl chain) which provides the softeningfunction by lubrication.

Any cationic substance which is substantive when rinsing with water onthe textile, and which is capable of making the textile soft, can beused as softener. A large number of these substances are known andcomprise quaternary compounds as follows:

-   -   (i) alkyl methyl quaternary ammonium compounds which have either        one C₁₈ to C₂₄ alkyl chain or two C12 to C30 alkyl chains, the        long-chain alkyl groups being most commonly derived from        hydrogenated tallow. Examples of these compounds are ditallow        dimethyl ammonium chloride, ditallow dimethyl ammonium        methylsulphate, tallow trimethyl ammonium chloride, dieicosyl        dimethyl ammonium chloride, tallow dimethyl(3-tallow        alkoxypropyl)ammonium chloride, ditetradecyl dimethyl ammonium        chloride, didodecyl diethyl ammonium acetate and tallow        trimethyl ammonium acetate,    -   (ii) amido alkoxylated quaternary ammonium compounds. Quaternary        compounds of this type can be prepared starting from fatty acids        or triglycerides and from an amine, for example        diethylenetriamine. The product is then alkoxylated with        ethylene oxide or propylene oxide and is quaternized with        dimethyl sulphate,    -   (iii) quaternized amidoimidazolines. Compounds of this type can        be obtained by heating the alkoxylated product of the reaction        of an amine and of a fatty acid or of a triglyceride as        described for type (ii) in order to carry out the cyclization        giving the imidazoline. The latter is then quaternized by        reaction, for example, with dimethyl sulphate. An example of a        compound of type (iii) is        2-heptadecyl-1-methyl-1-(2′-stearoylamidoethyl)imidazolinium        methyl sulphate,    -   (iv) polyamine salts and polyalkyleneimine salts,    -   (v) alkylpyridinium salts, for example, cetylpyridinium        chloride.

The cationic softeners generally preferred are those which containlong-chain fatty alkyl groups derived from tallow or from hydrogenatedtallow and the class of softeners generally preferred is that of type(i), i.e. the alkyl dimethyl ammonium compounds.

The compositions can contain other optional ingredients, for example,emulsifiers for polyorganosiloxanes, fragrances, optical brighteners anddyes. Particularly preferred optional ingredients of aqueous fabricsoftener compositions are certain nonionic emulsifiers, such as fattyacid esters of monoalcohols and polyalcohols, for example glycerylmonostearate, sorbitan monolaurate and sorbitan monooleate. These esterscan be used in proportions that are conventional for softeningcompositions, preferably from approximately 1 to 5% of the weight of theaqueous composition.

Those skilled in the art will be able to choose the best combination ofmonomers, crosslinking and/or transfer agents and polymerizationconditions according to their own knowledge and to the presentdescription, and also to the following examples.

EXEMPLARY EMBODIMENTS OF THE INVENTION

Synthesis and Evaluation in a Softening Formulation

A. Cationic Polymer Synthesis:

Example 1 (P1)

An aqueous phase of water-soluble monomers is prepared by mixing thefollowing compounds:

-   -   6.0% by weight of acrylamide at 50%    -   46.8% by weight of chloromethylated dimethylaminoethyl        methacrylate at 75%    -   1.3% by weight of ethoxylated behenyl methacrylate (EO 25)    -   0.03% by weight of diethylenetriaminepentaacetic acid,        pentasodium salt    -   0.05% by weight of sodium hypophosphite    -   0.02% by weight of methylenebisacrylamide    -   13.3% by weight of deionized water    -   the pH is adjusted to between 4.0 and 6.0 with citric acid.

An organic phase is prepared by adding the following compounds:

-   -   2.0% by weight of sorbitan monooleate    -   5.5% by weight of a stabilizing amphiphilic polymer    -   19.0% by weight of white mineral oil    -   6.0% by weight of light isoparaffinic light mineral oil.

The two phases are mixed in a 1 L stirred reactor, with the aqueousphase being poured into the organic phase, and then they are subjectedto a strong shear (of rotor stator type) for 1 minute in order to form awater-in-oil emulsion. This emulsion is then deoxygenated by bubblingnitrogen for 30 minutes.

The polymerization is carried out by simple addition of a redox coupleof the type sodium metabisulphite and tert-butyl hydroperoxide insolution in water.

After having reached the maximum polymerization temperature (adiabaticpolymerization) the emulsion is maintained at 65° C. for 1 h.

Vacuum distillation makes it possible to remove the water and thevolatile light oil so as to obtain a final concentration of polymer ofapproximately 58%.

The final step consists in adding an oil-in-water surfactant: 6.0% byweight of ethoxylated fatty alcohol (trideceth-6) is added to 100% byweight of distilled products.

Counter Example 1 (CP1)

The protocol of Example 1 is reproduced without ethoxylated behenylmethacrylate (EO 25).

Example 2 (P2)

Example 1 is reproduced in the absence of the crosslinking agent,methylenebisacrylamide.

Counter Example 2 (CP2)

Example 1 is reproduced in the absence of crosslinking agent and in theabsence of ethoxylated behenyl methacrylate (EO 25).

Example 3 (P3)

Example 1 is reproduced with the ethoxylated behenyl methacrylate (EO25) being replaced with ethoxylated cetyl methacrylate (EO 25).

Counter Example 3 (CP3)

Example 1 is reproduced, but with the ethoxylated behenyl methacrylatebeing replaced with ethoxylated dodecyl methacrylate (EO 25).

B. Preparation of a Softening Formulation Based on Quaternized Esters

94.5% by weight of deionized water at 50° C. is charged to a stirredreactor (150 rpm). 5.5% by weight of quaternized esters (StepantexVK-90) are then dispersed. After 15 minutes, the mixture is cooled toambient temperature and the pH is adjusted to 3.5 with citric acid.

The viscosity of the base obtained is then measured with a BrookfieldRVT viscometer, 10 rpm, 25° C. The value is 160 cps.

0.5% by weight of cationic polymer obtained from the examples of part A,is then added with stirring (350 rpm), until a homogeneous solution isobtained.

The viscosity of the final product obtained is then measured with aBrookfield RVT viscometer, 10 rpm, 25° C.

Results:

Apparent viscosity * Apparent viscosity ** Brookfield Brookfield Natureof the formulation RVT, 10 rpm RVT, 10 rpm Base “alone” 160 120 Base +0.5% P 1 1250 1450 Base + 0.5% CP 1 510 450 Base + 0.5% P 2 2600 2950Base + 0.5% CP 2 300 250 Base + 0.5% P 3 1050 1250 Base + 0.5% CP 3 320280 Base + 0.5% 480 450 Ciba ®RHEOVIS ®FRC * 1 h after obtaining ahomogeneous formulation, measurement carried out at 25° C. ** After 1month in an incubator at 50° C., measurement carried out at 25° C.

The polymers of the invention P1, P2 and P3 therefore make it possibleto significantly increase the viscosity of a softening composition andits stability over time.

What is claimed is:
 1. A method for softening laundry comprising thefollowing steps: providing a softening composition comprising at leastone textile softener and at least one thickener, the at least onethickener containing a cationic polymer obtained by polymerization: of acationic monomer; of a monomer with a hydrophobic nature, of formula(I):

wherein R1=H or CH₃ R2=alkyl chain having at least 16 carbon atoms X=O,m≧5, y=z=0; of a nonionic monomer; and applying the softeningcomposition to at least one textile material during a launderingprocess.
 2. The method of claim 1 further comprising the step of washingthe at least one textile material as part of the laundering process andwherein said step of applying the softening composition is performedsimultaneously with said washing step.
 3. The method of claim 1 furthercomprising the step of washing the at least one textile material as partof the laundering process and wherein said step of applying thesoftening composition is performed subsequent to said washing step. 4.The method of claim 1, wherein the thickener consists of a cationicterpolymer obtained by polymerization: of a cationic monomer; of amonomer with a hydrophobic nature, of formula (I):

wherein R1=H or CH₃ R2=alkyl chain having at least 16 carbon atoms X=O,m≧5, y=z=0; of a nonionic monomer.
 5. The method of claim 1, wherein thehydrophobic monomer is selected from the group consisting of:ethoxylated cetyl methacrylate (EO 25), ethoxylated behenyl methacrylate(EO 25) and mixtures of these compounds.
 6. The method of claim 1,wherein the hydrophobic monomer is ethoxylated behenyl methacrylate (EO25).
 7. The method of claim 1, wherein a content of hydrophobic monomerrepresents between 0.1% by weight and 20% by weight relative to theweight of the cationic polymer.
 8. The method of claim 7, wherein thecontent of hydrophobic monomer represents between 0.5% by weight and 5%by weight relative to the weight of the cationic polymer.
 9. The methodof claim 1, wherein the cationic monomer is selected from the groupconsisting of: diallyldialkylammonium salts; acidified or quaternizedsalts of dialkylaminoalkyl acrylates and methacrylates; and acidified orquaternized salts of dialkyl- aminoalkylacrylamides or methacrylamides.10. The method of claim 9, wherein the cationic monomer isdiallyldimethylammonium chloride (DADMAC).
 11. The method of claim 9,wherein the cationic monomer is selected from the group consisting ofacidified or quaternized salts of dialkylaminoethyl acrylate (ADAME) andacidified or quaternized salts of dialkylaminoethyl methacrylate(MADAME).
 12. The method of claim 1, wherein a content of cationicmonomer represents between 25% by weight and 99.9% by weight relative tothe weight of the cationic polymer.
 13. The method of claim 12, whereina content of cationic monomer represents between 50% by weight and 99.5%by weight relative to the weight of the cationic polymer.
 14. The methodof claim 1, wherein the cationic polymer is crosslinked in the presenceof a crosslinking agent selected from the group consisting of:methylenebisacrylamide (MBA), ethylene glycol diacrylate, polyethyleneglycol dimethacrylate, diacrylamide, cyanomethyl acrylate, vinyloxyethylacrylate or methacrylate, triallylamine, formaldehyde, glyoxal,compounds of glycidyl ether type, epoxies, and mixtures of thesecompounds.
 15. The method of claim 14, wherein the cationic polymer iscrosslinked in the presence of a transfer agent selected from the groupconsisting of isopropyl alcohol, sodium hypophosphite, mercaptoethanoland mixtures of these compounds.
 16. The method of claim 1, wherein thecationic polymer is obtained by inverse emulsion polymerization.
 17. Themethod of claim 1, wherein the cationic polymer is in the form of aninverse emulsion comprising an oily phase, an aqueous phase, at leastone water-in-oil (W/O) emulsifier, at least one oil-in-water (O/W)emulsifier and from 20% to 60% by weight of said cationic polymer. 18.The method of claim 1, wherein the cationic polymer is obtained bypolymerization: of chloromethylated dimethylaminoethyl methacrylate; ofacrylamide; and of ethoxylated behenyl methacrylate (EO 25).
 19. Themethod of claim 1, wherein the cationic polymer is obtained bypolymerization: of chloromethylated dimethylaminoethyl methacrylate; ofacrylamide; and of ethoxylated cetyl methacrylate (EO 25).
 20. Themethod of claim 1, wherein a content of thickener represents 0.05% to10% relative to the weight of the softening composition.